Question

A train left Podunk and traveled west at 70 km/hr. Two hours later, another train left Podunk and traveled east at 90 km/hr. How many hours had the first train traveled when they were 1420 km apart

Answer 1

The first train going west traveled by 7 hours and 45 minutes

Explanation:

Given as :

The speed of west going train = 70 kmph

The speed of east going train = 90 kmph

Distance between both the train is 1420 km

Let the distance cover by east going train = x km

So, The distance cover by west going train = (1420 - x) km

The west going train travel for T hour

And The east going train travel for ( T + 2 ) hour

Now, From Distance = speed × time

For east going train

x = 90 × ( T + 2 )

Or, x = 90 T + 180

For west going train

1420 - x = 70 × T

So, from above equations :

1420 - (90 T + 180 ) = 70 T

Or, 1420 - 180 = 70 T + 90 T

Or, 1240 = 160 T

∴ T =
`(1240)/(160)`

So, T = 7.75 hours

Or, T = ( 7 +
`(75)/(100)` ) hours

Or, T = (7 +
`(3)/(4)` ) hours

Or, T = 7 hours and 45 minutes

Hence The first train going west traveled by 7 hours and 45 minutes Answer